1. Field of the Invention
The present invention relates to an array substrate for a display device, and more specifically, to an array substrate for a display device, capable of preventing a defect due to static electricity charged on an electrode.
2. Discussion of the Related Art
Recently, flat panel displays (FPDs) are becoming increasingly important with the development of multimedia. Accordingly, several display devices, such as a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED), and an organic light emitting display (OLED) have been put to practical use. Of theses, the organic light emitting display is being considered as a next-generation display device since the organic light emitting display exhibits a high-speed response of 1 ms or less and low power consumption, and has self-light emission characteristics, causing no problems in the viewing angle.
The display device is driven in a passive matrix manner and an active matrix manner using thin film transistors. While the driving is implemented by forming positive electrodes and negative electrodes to cross each other and selecting a line according to the passive matrix manner, the driving is implemented by respectively connecting thin film transistors to pixels and maintaining a voltage through the capacitance of capacitors connected to gate electrodes of the thin film transistors.
Generally, the liquid crystal display is driven using optical anisotropy and polarization of liquid crystals. Since the liquid crystal has a thin and long structure, it has orientation in view of arrangement of liquid crystal molecules. The orientation in the arrangement of the liquid crystal molecules can be controlled by applying an electric field to the liquid crystals. Therefore, when the orientation in the arrangement of liquid crystal molecules is arbitrarily controlled, the arrangement of liquid crystal molecules are changed, the light is refracted in a direction of the arrangement of the liquid crystal molecules due to optical anisotropy to express image information.
The liquid crystal display is attracting more attention since an active matrix structure in which thin film transistors and pixel electrodes connected to the thin film transistors are arranged in a matrix type is excellent in view of resolution and video display capacity. The liquid crystal display is composed of a color filter substrate with a common electrode, an array substrate with pixel electrodes, and liquid crystals interposed between the two substrates. In this liquid crystal display, the common electrode and the pixel electrodes drive the liquid crystals by an electric field applied above and below the liquid crystals, and excellent transmittance and aperture ratio are obtained. The driving of the liquid crystals by the electric field applied above and below the liquid crystals causes a problem that the viewing angle property is not excellent.
An in-plane switching mode liquid crystal display having excellent viewing angle property has been proposed in order to solve the problem. As for the in-plane switching mode liquid crystal display, liquid crystals are driven by using a horizontal field between a pixel electrodes and a common electrode, thereby improving the viewing angle property. The electrode positioned at the top of the in-plane switching mode liquid crystal display is directly contacted with an alignment layer. The static electricity generated by a rubbing process of the alignment layer may be charged on the electrode. However, since there is no path through which the charged static electricity can be discharged from the electrodes, panel scribing is conducted while the static electricity is charged, and thus the charged static electricity is kept while the liquid crystals are driven, thereby causing a screen whitening defect at the time of the AP lighting test.